The present invention relates to an oil supply unit of a linear compressor, and more particularly, to an oil supply unit of a linear compressor which is capable of facilitating fabricating and assembling an oil suction valve.
As is known, a linear compressor is an equipment for compressing a coolant by directly moving reciprocally by means of a magnet and a coil instead of a crank shaft.
FIG. 1 shows a general linear compressor in accordance with a conventional art. As shown in the drawing, the linear compressor includes a compressive unit xe2x80x98Cxe2x80x99 installed in a well-closed container xe2x80x98Vxe2x80x99 filled with oil at its bottom in the horizontal direction for sucking, compressing and discharging a coolant, and an oil supply unit xe2x80x98Oxe2x80x99 fixed at an outside of the compressive unit xe2x80x98Cxe2x80x99 for supplying oil to friction portions of construction elements.
The construction of the compressive unit xe2x80x98Cxe2x80x99 will now be described in detail.
The compressive unit xe2x80x98Cxe2x80x99 includes a frame 1 installed inside the well-closed container xe2x80x98Vxe2x80x99, a cylinder 2 inserted into a through hole formed at the central portion of the frame 1, a piston 3 inserted inside the cylinder and for being moved linearly and reciprocally by the driving of a linear motor, and a discharge cover 5 having a discharge valve 4 that opens and closes the cylinder 2 according to the reciprocal movement of the piston 3, and combined to one side of the cylinder 2 to be opened.
A first oil pocket 1b is formed at the inner circumferential surface of the through hole of the frame 1, communicating with the discharging side of the oil supply unit xe2x80x98Oxe2x80x99 by an oil inlet passage 1a. A second oil pocket 3a is formed at the outer circumferential surface of the piston 3. An oil through hole 2a is formed at the cylinder 2, rendering the first oil pocket 1b to be communicated with the second oil pocket 3a. 
An oil circulation path 1d is formed at the uppermost portion of the first oil pocket 1b by the outer circumferential surface of the cylinder 2, the through hole of the frame 1 and the discharge cover 5, communicating with an oil communicating path 1c. An oil discharge hole 1e is formed at the lowermost portion of the oil circulating path 1d, to return the oil that circulated through the oil circulating path 1d to the well-closed container xe2x80x98Vxe2x80x99.
The construction of the oil supply unit xe2x80x98Oxe2x80x99 will now be described in detail.
FIG. 2 is a vertical-sectional view of the oil supply unit of the linear compressor in accordance with the conventional art. FIG. 3A is a plan view of an oil suction valve of the oil supply unit of the linear compressor in accordance with the conventional art, and FIG. 3B is a plan view of an oil discharge valve of the oil supply unit of the linear compressor in accordance with the conventional art.
As shown in the drawings, the oil supply unit xe2x80x98Oxe2x80x99 includes an oil cylinder 21 attached at the bottom of the compressive unit xe2x80x98Cxe2x80x99, an oil piston 22 inserted into the oil cylinder 21, dividing the inside of the oil cylinder 21 to a suction space S1 and a discharge space S2, a first and a second oil springs 23A and 23B of which each one end elastically support both ends of the oil piston against the oil cylinder 21, an oil suction cover 24 and an oil discharge cover 25 for respectively supporting each other end of the first and the second oil springs 23A and 23B, and respectively fixing the both ends of the oil cylinder 21 to the compressive unit xe2x80x98Cxe2x80x99, an oil suction valve 26 positioned between the outlet of the oil piston 22 and the one end portion of the second oil spring 23B, to be supported by the second oil spring 23B, and an oil discharge valve 27 positioned at one side of the other end portion of the second oil spring 23B and being mounted inside the oil discharge cover 25.
The oil piston 22 is inserted in a manner that is outer circumferential surface slidably contacts the inner circumferential surface of the oil cylinder 21, and an oil passage 22a is penetratingly formed in the lengthy direction at its inner central portion.
In a spiral form, the oil suction valve 26 is inserted in the oil cylinder 21 and tightly supported by the second oil spring 23B at the outlet portion of the oil piston 22. Meanwhile, in a rectangular form, the oil discharge valve 27 is adhered at the outer surface of the discharging side of the oil cylinder 21, being supported by the oil discharge cover 25.
Reference numeral 6 denotes a stator assembly a stator, and reference numeral 7 denotes a magnet assembly, a rotor, 8 denotes a cover, 9 denotes a main spring, and 10 denotes a suction pipe.
The operation of the oil supply unit of the linear compressor of the conventional art constructed as described above will now be explained.
The compressive unit xe2x80x98Cxe2x80x99 is vibrated in the horizontal direction along with the magnet assembly according to the linear reciprocal movement of the magnet assembly 7, the rotor of the linear motor, and the vibration is transferred to the oil supply unit xe2x80x98Oxe2x80x99 fixed at the compressive unit xe2x80x98Cxe2x80x99, rendering the oil supply unit xe2x80x98Oxe2x80x99 to move reciprocally. At this time, the oil piston 22 is slidably inserted to the oil cylinder, so that the oil is sucked and discharged by the inertial force corresponding to the reciprocal movement of the oil cylinder 21.
The thusly pumped oil by the oil supply unit xe2x80x98Oxe2x80x99 is induced to the first oil pocket 1b through the oil inlet passage 1a and then induced to the second oil pocket 3a through the oil through hole 2a, cooling the heat generated at the outer circumferential surface of the cylinder 2 and the heat generated at the linear motor and lubricating the sliding portion between the cylinder 2 and the piston 3. And then, the oil is induced to the oil circulating path 1d through the first oil pocket 1b and the oil communicating path 1c, which is circulated the cylinder 2 and the discharge cover 4, while cooling it, and then returns to the well-closed container xe2x80x98Vxe2x80x99 through the oil discharge hole 1e. 
The operation that the oil supply unit xe2x80x98Oxe2x80x99 pumps the oil will now be described with reference to FIGS. 4A and 4B.
First, when the oil cylinder 21 is moved in the xe2x80x98Axe2x80x99 direction of FIG. 4A, resultantly, the oil piston 22 is moved in the xe2x80x98Bxe2x80x99 direction, so that the oil that filled the discharge space xe2x80x98S2xe2x80x99 is pushed toward the oil discharge cover 25 while oil is induced to the suction space xe2x80x98S1xe2x80x99 to be filled.
At this time, the oil suction valve 26 is closed, closing the oil passage 22a of the oil piston 22, while the oil discharge valve 27 is pulled back in the xe2x80x98Bxe2x80x99 direction, opening the discharging side of the oil cylinder 21.
Reversely, in case that the oil cylinder 21 is moved in the xe2x80x98Bxe2x80x99 direction of Figure B, resultantly, the oil piston 22 is moved in the xe2x80x98Axe2x80x99 direction, so that the pressure of the discharge space xe2x80x98S2xe2x80x99 becomes relatively low compared to that of the suction space xe2x80x98S1xe2x80x99, rendering the oil of the suction space xe2x80x98S1xe2x80x99 to be moved to the discharge space xe2x80x98S2xe2x80x99.
At this time, the first oil spring 23A is compressed while the second oil spring 23B is extended, and the oil suction valve 26 is opened while the oil discharge valve 27 is rotated in the xe2x80x98Axe2x80x99 direction to close the discharging side of the oil cylinder 21 to thereby prevent backflow of the oil.
However, as to the oil supply unit of the conventional linear compressor, since the oil suction valve controlling the inlet and outlet of the oil is made small to be mounted within the cylinder having small diameter, its fabrication and assembling is not easy.
Therefore, it is an object of the present invention to provide an oil supply unit of a linear compressor which is capable of improving a productivity by facilitating fabrication and assembling of a valve that controls inlet and outlet of oil.
In order to achieve the above object, there is provided an oil supply unit of a linear compressor including: a well-closed container filled with oil; a frame installed within the well-closed container; a cylinder fixed at the frame; a piston inserted in the cylinder and being linearly and reciprocally moved by a linear motor; an oil cylinder fixed at the lower portion of the frame so as to be put in the oil filling the well-closed container, and being vibrated in the horizontal direction according to the reciprocal movement of the piston; an oil piston inserted in the oil cylinder in a manner of dividing the inside of the oil cylinder to a suction space and a discharge space that are communicated to each other, and being vibrated in the horizontal direction; an oil suction valve installed at the outer side of the suction side of the oil cylinder, for opening and closing the suction side of the oil cylinder; an oil discharge valve installed at the outer side of the discharging side of the oil cylinder, for opening and closing the discharging side of the oil cylinder: an oil suction cover for covering the suction side of the oil cylinder and having the oil suction valve inside thereof; and an oil discharge cover forming an oil inlet passage along with the frame, opening the discharging side of the oil cylinder, and having the oil discharge valve inside thereof.